Pressure-welding device and pressure-welding method

Abstract

To provide a pressure-welding device that can achieve small-sizing of itself and can be easily applied to an actual production line by comprising simple configuration, and a pressure-welding method.SOLUTION: A pressure-welding device 1000 comprises a current application device 50, on a first electrode 11 and a second electrode 21, for conducting a low current to a first work-piece 1 and a second work-piece 2 so as to become a molten below of the first work-piece 1 and the second work-piece 2 or less in the state that the first work-piece 1 and the second work-piece 2 are sandwiched by the first electrode 11 and the second electrode 21. A first pressurizing shaft 13 includes a protrusion 13a, which extends to a second pressurizing shaft 23 side, on a side facing the second pressurizing shaft 23. The second pressurizing shaft 23 includes a recess 23a, which receives the protrusion 13a, on a side facing the first pressurizing shaft 13.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a pressure welding apparatus and a pressure welding method. [Background technology]

[0002] JP 2017-177206 A (Patent Document 1) discloses an invention relating to a mechanical clinch-jointed part and a manufacturing method thereof, in which the mechanical clinch-jointed part is a clinch-jointed part made of two or more steel plates and has at least one joint with a peel strength of 0.200 kN / mm or more. It also discloses that after a heating process in which the steel plates are heated to a certain level or higher, in the heating process, it is preferable to satisfy a predetermined relational expression in the relationship between the carbon equivalent of the steel plates, the bottom dead center holding time during mechanical clinch joining, and the joining start temperature.

[0003] JP 2019-883 A (Patent Document 2) discloses a method for sandwiching a laminated metal foil consisting of two or more metal foils between a first metal plate and a second metal plate, and joining the metal plates and the laminated metal foil by crimping. The method includes a laser light irradiation process in which, before crimping with a punch and a die, a laser light is irradiated near the intended crimping position of the second metal plate placed on the punch side, thereby heating the second metal plate to a temperature that does not melt and that promotes plastic flow of the second metal plate when crimping is performed, and a process of performing crimping in a heated state of the second metal plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-177206 A [Patent Document 2] JP 2019-883 A Summary of the Invention [Problem to be solved by the invention]

[0005] Mechanical clinching is generally a high pressure joining process using cold plastic processing, and has a die and a punch. The punch presses the plate, causing the material to plastically flow into the shape of the die, forming an interlock. In order to cause the material to flow locally, a plate holder is also required in addition to the die and punch.

[0006] A mechanical clinching method using a resistance spot welding device is also known, in which mechanical fastening can be achieved by hot plastic processing that utilizes both the pressure mechanism and the current-carrying mechanism of the resistance spot welding device.

[0007] However, conventional mechanical clinching requires high pressure, so the mechanism for achieving high pressure is also large-scale equipment, and it is difficult to mount a joining gun on a robot hand with a payload of 210 kg or less. Also, in order to make the material flow locally, a mechanism for holding the plate is required in addition to the die and punch, which narrows the range of application to base material shapes such as flanges.

[0008] Furthermore, when the electrode tip for resistance spot welding is made into a die and punch type, there are currently issues with its application to actual production lines, such as the long current flow time required to achieve a joint and the durability of the die and punch type electrodes.

[0009] An object of the present disclosure is to provide a pressure welding apparatus and a pressure welding method that, by having a simple configuration, can be made smaller in size and can be easily applied to an actual production line. [Means for solving the problem]

[0010] [1]: The present disclosure provides a pressure welding device that applies pressure to a first workpiece made of metal and a second workpiece made of metal from both sides in a thickness direction of the first workpiece and a second workpiece, thereby joining the first workpiece and the second workpiece to each other, the pressure welding device comprising a pair of first and second pressure shafts capable of applying pressure to the first and second workpieces from both sides in a thickness direction of the first workpiece and the second workpiece, a first electrode that is annularly disposed around the axis of the first pressure shaft, and a current that is disposed opposite the first electrode and is connected to the axis of the second pressure shaft. a second electrode arranged in a ring shape surrounding the first workpiece and the second workpiece; and a current application device for passing a low current through the first electrode and the second electrode so that the temperatures of the first workpiece and the second workpiece are below the melting points of the first workpiece and the second workpiece when the first electrode and the second electrode are sandwiched between them, wherein the first pressure applying shaft includes a convex portion extending towards the second pressure applying shaft on a side facing the second pressure applying shaft, and the second pressure applying shaft includes a concave portion for receiving the convex portion on a side facing the first pressure applying shaft.

[0011] [2]: The pressure welding apparatus according to [1], wherein the first electrode and the second electrode are made of at least one material selected from the group consisting of copper, a copper alloy, tungsten, and molybdenum.

[0012] [3]: The crimping method of the present disclosure is a crimping method using the crimping device described in either [1] or claim [2], and includes the steps of: clamping the first workpiece and the second workpiece between the first electrode and the second electrode; using the current application device, passing a low current through the first electrode and the second electrode so that the temperature of the first workpiece and the second workpiece is equal to or lower than the melting points of the first workpiece and the second workpiece, thereby softening the first workpiece and the second workpiece; and while the first workpiece and the second workpiece are held between the first electrode and the second electrode, clamping the first workpiece and the second workpiece with the first pressure shaft and the second pressure shaft, and applying pressure so that the convex portion of the first pressure shaft fits into the concave portion of the second pressure shaft, thereby forming a crimping area between the first workpiece and the second workpiece. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a pressure welding apparatus and a pressure welding method that, by being provided with a simple configuration, can reduce the size of the apparatus and can be easily applied to an actual production line. [Brief description of the drawings]

[0014] [Figure 1] 1 is a vertical cross-sectional view showing a schematic diagram of a pressure welding device according to an embodiment of the present invention; [Diagram 2] FIG. 4 is a perspective view of the first pressure applying shaft as viewed from the pressure applying surface side. [Diagram 3] FIG. 4 is a perspective view of the second pressure applying shaft as viewed from the pressure applying surface side. [Figure 4] FIG. 4 is a cross-sectional view showing a schematic state in which current is applied to each workpiece. [Diagram 5] 1A and 1B are diagrams showing the state in which each workpiece is pressed by a pair of pressure shafts. [Figure 6] FIG. 4 is a cross-sectional view showing the final joining state of the workpieces. [Figure 7] This is a schematic diagram showing good current-flow and pressure-welding marks. [Figure 8] FIG. 1 is a schematic diagram showing poor current-pressure welding marks. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The pressure welding apparatus and pressure welding method of the embodiment will be described below with reference to the drawings. In the comparative examples and the embodiment described below, when the number, amount, etc. are mentioned, the scope of the present invention is not necessarily limited to the number, amount, etc., unless otherwise specified. The same reference numbers are given to the same parts and corresponding parts, and duplicated descriptions may not be repeated. It is intended from the beginning that the configurations in the embodiment will be used in appropriate combination.

[0016] [Pressure welding device 1000] An embodiment of a pressure welding device 1000 will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a vertical cross-sectional view showing the pressure welding device 1000 in outline, Fig. 2 is a perspective view seen from the pressure surface side of the first pressure shaft 13, and Fig. 3 is a perspective view seen from the pressure surface side of the second pressure shaft 23.

[0017] The pressure welding apparatus 1000 is an apparatus for joining a plurality of workpieces stacked on top of one another by passing an electric current through the plurality of workpieces to form softened regions in the plurality of workpieces and plastically deforming the softened regions.

[0018] In this embodiment, the multiple workpieces include a first workpiece 1 and a second workpiece 2. The first workpiece 1 and the second workpiece 2 are made of metal such as iron or aluminum. In general, the first workpiece 1 and the second workpiece 2 may be made of different materials or the same type of material. The first workpiece 1 and the second workpiece 2 are formed, for example, in a flat plate shape.

[0019] The pressure welding device 1000 has a pair of pressure shafts, a first pressure shaft 13 and a second pressure shaft 23. The first pressure shaft 13 and the second pressure shaft 23 are capable of applying pressure to the first work 1 and the second work 2 from both sides in the thickness direction. The first pressure shaft 13 and the second pressure shaft 23 are driven to reciprocate along their axial directions by a drive source (such as a servo press machine) not shown.

[0020] The first pressure applying shaft 13 is a so-called punch type, and includes, on the side facing the second pressure applying shaft 23, a convex portion 13a extending toward the second pressure applying shaft 23. The second pressure applying shaft 23 is a so-called die type, and includes, on the side facing the first pressure applying shaft 13, a concave portion 23a for receiving the convex portion 13a.

[0021] The pressure welding device 1000 has a first electrode 11 arranged in a ring shape so as to surround the axis of a first pressure applying shaft 13, and a second electrode 21 arranged opposite the first electrode 11 and arranged in a ring shape so as to surround the axis of a second pressure applying shaft 23.

[0022] The first electrode 11 has a first replacement electrode 11a and a first body electrode 11b, and the first replacement electrode 11a is provided detachably to the first body electrode 11b and is provided so as to be periodically replaced by a screw-on structure. The second electrode 21 has a second replacement electrode 21a and a second body electrode 21b, and the second replacement electrode 21a is provided detachably to the second body electrode 21b and is provided so as to be periodically replaced by a screw-on structure. The first electrode 11 and the second electrode 21 are preferably made of copper. In addition to copper, at least one material selected from copper alloy, tungsten, and molybdenum may be used.

[0023] A current application device 50 is connected to the first electrode 11 and the second electrode 21, which applies a current to generate resistance heat below the melting point at the contact point between the first work 1 and the second work 2 while the first pressure application shaft 13 and the second pressure application shaft 23 are holding the first work 1 and the second work 2 together.

[0024] [Pressure welding method] A pressure welding method using pressure welding apparatus 1000 having the above-mentioned structure will be described with reference to Fig. 4 to Fig. 8. Fig. 4 is a cross-sectional view showing a schematic state in which current is being applied to each workpiece, Fig. 5 is a view showing a state in which each workpiece is pressed by a pair of pressure shafts, Fig. 6 is a cross-sectional view showing a final joined state of the workpieces, Fig. 7 is a schematic view showing good current application and pressure welding marks, and Fig. 8 is a schematic view showing poor current application and pressure welding marks.

[0025] 4, the first electrode 11 and the second electrode 21 are each moved toward the work (in the direction of the arrow F1 in FIG. 4), and the first work 1 and the second work 2 are sandwiched between the first electrode 11 and the second electrode 21. At this time, since the first electrode 11 and the second electrode 21 each have an annular shape and pressurize and sandwich the first work 1 and the second work 2, the first work 1 and the second work 2 do not move even in the crimping process described below. As a result, even if this crimping device 1000 is mounted on a robot hand, for example, the fixation of the work to be processed can be stably performed.

[0026] Next, using the current application device 50, a low current is applied to the first electrode 11 and the second electrode 21 so that the temperature is below the melting points of the first workpiece 1 and the second workpiece 2. This makes it possible to soften the area indicated by A in Fig. 4. Although the current value differs depending on the plate thickness and material of the first workpiece 1 and the second workpiece 2, a current of about 1.0 kA to 6.0 kA is applied for about 0.05 to 0.3 seconds.

[0027] 5, while the first work 1 and the second work 2 are sandwiched between the first electrode 11 and the second electrode 21, the first pressure shaft 13 and the second pressure shaft 23 are moved toward the work (in the direction of the arrow F2 in FIG. 5) to sandwich the first work 1 and the second work 2 between the first pressure shaft 13 and the second pressure shaft 23, and pressure is applied so that the convex portion 13a of the first pressure shaft 13 fits into the concave portion 23a of the second pressure shaft 23, thereby forming a crimped region R1 between the first work 1 and the second work 2. The pressure varies depending on the plate thickness and material of the first work 1 and the second work 2, but the crimp is formed with a pressure of about 5 kN to 30 kN.

[0028] The crimping region R1 will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing the final joining state of the workpieces. According to the crimping method using this crimping device 1000, it is possible to form an interlock region IL where the first workpiece 1 is pressed into the second workpiece 2 while the first workpiece 1 and the second workpiece 2 are in a softened state.

[0029] In the pressure welding apparatus and method disclosed herein, the first electrode 11 and the second electrode 21 are disposed around the first pressure shaft 13 and the second pressure shaft 23, and therefore, after the pressure welding method is performed, a ring-shaped current-pressure mark TD1 may be formed as shown in Fig. 7. In the ring-shaped current-pressure mark TD1, the current mark portion of the outer ring can be confirmed when the electrodes are in even contact and current is applied, but may not be visible when the current density is low. Also, the current mark portion of the outer ring may remain as an indentation when the pressure is high.

[0030] On the other hand, if the electrode is not in proper contact with the workpiece or if the electrode is not annular, island-shaped current-pressure marks TD2 will be formed as shown in FIG.

[0031] As described above, the pressure welding apparatus 1000 of the present disclosure also corresponds to a hot plastic processing method using the resistance heating of the first workpiece 1 and the second workpiece 2, and therefore can join with a lower pressure than the existing mechanical clinching. For example, in the case of a cold plastic processing method, the driving force of the first pressure shaft 13 and the second pressure shaft 23 requires about 50 to 95 kN, depending on the material, but in the present disclosure, the interlock region IL can be formed with a driving force of 30 kN.

[0032] Furthermore, the pressure welding device 1000 of the present disclosure can be mounted on a robot hand with a payload of 210 kg or less. This allows the range of application to be expanded to actual production lines for automobiles, etc. Furthermore, in addition to being able to locally soften the material by resistance heating, the electrode itself acts as a pressure retainer, eliminating the need for a separate sheet retainer.

[0033] Furthermore, since this method is also considered a thermoplastic processing method as described above, it can be applied not only to joining dissimilar materials such as aluminum and iron, but also to joining high-strength homogeneous materials and joining die-cast materials.

[0034] Furthermore, since the first electrode 11 and the second electrode 21 are arranged separately from the first pressure shaft 13 and the second pressure shaft 23, the durability of the electrodes is improved. In the case of normal resistance spot welding, the maximum force is about 5 kN to 10 kN, but in the case of the pressure welding device 1000 of the present disclosure, the workpiece can be clamped with a higher force than normal resistance spot welding, so electrode deformation, which occurs in mechanical clinching methods using a resistance spot welding device, does not occur, and crimping joining can be achieved in a short period of time.

[0035] Thus, the pressure welding apparatus and pressure welding method disclosed herein have a simple configuration, which allows the apparatus to be made smaller and easier to apply to an actual production line.

[0036] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0037] 1 first workpiece, 2 second workpiece, 11 first electrode, 11a first replacement electrode, 11b first main body electrode, 13 first pressure shaft, 13a convex portion, 21 second electrode, 21a second replacement electrode, 21b second main body electrode, 23 second pressure shaft, 23a concave portion, 50 current application device, 1000 pressure welding device.

Claims

1. 1. A pressure welding device that applies pressure to a first workpiece made of metal and a second workpiece made of metal from both sides in a thickness direction of the first workpiece and passes current through the first workpiece and the second workpiece to join the first workpiece and the second workpiece to each other, a pair of first and second pressurizing shafts capable of applying pressure to the first and second workpieces from both sides in a thickness direction of the first and second workpieces; A first electrode disposed annularly so as to surround the first pressure shaft; a second electrode disposed opposite the first electrode and annularly disposed around the second pressurizing shaft; a current application device for applying a low current to the first electrode and the second electrode so that the current is equal to or lower than the melting points of the first workpiece and the second workpiece when the first workpiece and the second workpiece are sandwiched between the first electrode and the second electrode; Equipped with the first pressure applying shaft includes a protrusion extending toward the second pressure applying shaft on a side facing the second pressure applying shaft, The second pressure applying shaft includes a recess for receiving the protrusion on a side facing the first pressure applying shaft. Pressure welding device.

2. The first electrode and the second electrode are made of at least one material selected from copper, a copper alloy, tungsten, and molybdenum.

2. The insulation displacement device according to claim 1.

3. A pressure welding method using the pressure welding apparatus according to claim 1 or 2, comprising: a step of sandwiching the first workpiece and the second workpiece between the first electrode and the second electrode; a step of applying a low current to the first electrode and the second electrode using the current application device so that the first workpiece and the second workpiece are at or below the melting points of the first workpiece and the second workpiece, thereby softening the first workpiece and the second workpiece; a step of sandwiching the first workpiece and the second workpiece with the first pressure shaft and the second pressure shaft while the first workpiece and the second workpiece are sandwiched between the first electrode and the second electrode, and applying pressure so that the convex portion of the first pressure shaft fits into the concave portion of the second pressure shaft, thereby forming a crimped region between the first workpiece and the second workpiece; The pressure welding method comprises:

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